tests: add pidfd_open() tests

This adds testing for the new pidfd_open() syscalls. Specifically, we test:
- that no invalid flags can be passed to pidfd_open()
- that no invalid pid can be passed to pidfd_open()
- that a pidfd can be retrieved with pidfd_open()
- that the retrieved pidfd references the correct pid

Signed-off-by: Christian Brauner <christian@brauner.io>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jann Horn <jannh@google.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org

1 files changed, 5 insertions, 43 deletions

diff --git a/tools/testing/selftests/pidfd/pidfd_test.c b/tools/testing/selftests/pidfd/pidfd_test.c
index 9929dc6fa2d6..7eaa8a3de262 100644
--- a/tools/testing/selftests/pidfd/pidfd_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_test.c
@@ -18,16 +18,18 @@
 #include <time.h>
 #include <unistd.h>
 
+#include "pidfd.h"
 #include "../kselftest.h"
 
+#ifndef __NR_pidfd_send_signal
+#define __NR_pidfd_send_signal -1
+#endif
+
 #define str(s) _str(s)
 #define _str(s) #s
 #define CHILD_THREAD_MIN_WAIT 3 /* seconds */
 
 #define MAX_EVENTS 5
-#ifndef __NR_pidfd_send_signal
-#define __NR_pidfd_send_signal 424
-#endif
 
 #ifndef CLONE_PIDFD
 #define CLONE_PIDFD 0x00001000
@@ -91,28 +93,6 @@ static int test_pidfd_send_signal_simple_success(void)
 	return 0;
 }
 
-static int wait_for_pid(pid_t pid)
-{
-	int status, ret;
-
-again:
-	ret = waitpid(pid, &status, 0);
-	if (ret == -1) {
-		if (errno == EINTR)
-			goto again;
-
-		return -1;
-	}
-
-	if (ret != pid)
-		goto again;
-
-	if (!WIFEXITED(status))
-		return -1;
-
-	return WEXITSTATUS(status);
-}
-
 static int test_pidfd_send_signal_exited_fail(void)
 {
 	int pidfd, ret, saved_errno;
@@ -158,13 +138,6 @@ static int test_pidfd_send_signal_exited_fail(void)
 }
 
 /*
- * The kernel reserves 300 pids via RESERVED_PIDS in kernel/pid.c
- * That means, when it wraps around any pid < 300 will be skipped.
- * So we need to use a pid > 300 in order to test recycling.
- */
-#define PID_RECYCLE 1000
-
-/*
  * Maximum number of cycles we allow. This is equivalent to PID_MAX_DEFAULT.
  * If users set a higher limit or we have cycled PIDFD_MAX_DEFAULT number of
  * times then we skip the test to not go into an infinite loop or block for a
@@ -172,17 +145,6 @@ static int test_pidfd_send_signal_exited_fail(void)
  */
 #define PIDFD_MAX_DEFAULT 0x8000
 
-/*
- * Define a few custom error codes for the child process to clearly indicate
- * what is happening. This way we can tell the difference between a system
- * error, a test error, etc.
- */
-#define PIDFD_PASS 0
-#define PIDFD_FAIL 1
-#define PIDFD_ERROR 2
-#define PIDFD_SKIP 3
-#define PIDFD_XFAIL 4
-
 static int test_pidfd_send_signal_recycled_pid_fail(void)
 {
 	int i, ret;